Source: Hemoglobin; Public Domain: http://www.epa.gov/nerlesd1/chemistry/ice/48aasms.htm
The actual iron atom within the heme group to which oxygen binds.
This is the iron group in the center of each globular protein in a hemoglobin molecule; therefore one hemoglobin molecule has four heme groups associated to it. The heme group is what oxygen binds to when red blood cells are circulating oxygen throughout the body.
A term used to describe the protein structure of hemoglobin.
The term used to describe when oxygen is bound to hemoglobin; oxygen + hemoglobin = oxyhemoglobin.
A quaternary pigment protein found on red blood cells, hemoglobin is primarily used to transport oxygen and some carbon dioxide throughout the blood.